The present invention relates to mixed aluminium oxides, their production process and their use.
More specifically the present invention relates to mixed aluminium oxides obtained in the form of monocrystals and more particularly used in the field of microlasers for integrated optics or telecommunications by optical fibres, as well as in the field of power lasers emitting in the infrared permitting, for example, the processing of materials, the performance of photochemical reactions and controlled thermonuclear fusion.
At present mixed aluminium oxides are known and in particular mixed aluminates of lanthanum-magnesium, cerium-magnesium, lanthanum-manganese and cerium-manganese of chemical formula LnMAl.sub.11 O.sub.19 in which Ln stands for the lanthanum or cerium and M for the magnesium or manganese. These mixed aluminium oxides produced by the Philips company can be doped by luminescent ions such as Ce.sup.3+, Tb.sup.3+, Eu.sup.2+, Mn.sup.2+ ions.
These doped or undoped mixed oxides obtained only in the form of powders have important luminescent properties (display device, etc.), but have no laser effect. Their production processes and their optical properties (luminescence) are described in a number of articles such as, for example, an article entitled "Cerium and Terbium luminescence in LaMgAl.sub.11 O.sub.19 ", published in the Journal of Luminescence 6, 1973, pp. 425 to 431 and in another article entitled "Red Mn.sup.2+ luminescence in hexagonal aluminates" published in the Journal of luminescence 20, 1979, pp. 99 to 109.